Preventing discoloration of fuel oils



Patented June 9, 1953 PREVENTING DISCOLORATION OF FUEL OILS v Ralph B. Thompson, Hinsdale, and Joseph A.

Chenicek, Bensenville, 111., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application April 6, 1950, Serial No. 154,438

8 Claims.

This invention relates to a novel method of preventing discoloration of fuel oils and more particularly to the use of a particular additive in fuel oils to prevent discoloration thereof.

The fuel oils to which the present application 7 is directed, in general, comprise hydrocarbon distillates boiling above the range of gasoline and thus include particularly kerosene, #1 fuel oil, #2 fuel oil, burner oil, diesel oil, etc., as well as compositions containing these oils, such as jet fuels, tractor fuels, etc. These oils in storage tend to undergo discoloration and turn from a light to a dark color. Most consumers object to the dark colored oils and, therefore, will not purchase the discolored oils at the premium price normally prevalent for the light colored oils. In fact, some of the specifications for these oils include a minimum color requirement which the darkened oils cannot meet.

In one embodiment the present invention relates to a method of preventing the discoloration of fuel oil which comprises adding thereto the condensation product of a cyclic and more particularly a cyclic carbonyl compound and an alkanol amine.

In a specific embodiment the present invention 1 relates to a method of preventing discoloration of fuel oil which comprises adding thereto from about 0.0005% to about 0.1% by weight of the condensation product of benzaldehyde and, propanol amine.

The additives of the present invention are illustrated by the following general structure:'

where R is selected from an aryl group and an unsaturated heterocyclic ring containing as the hetero atom an element selected from oxygen, sulfur and nitrogen; R. is selected from hydrogen and a hydrocarbon group; X is selected from an alkylene and an arylene group; and R." is selected from hydrogen and a hydrocarbongroup. I Referring to the structure hereinbefore set forth, it is preferred that R. comprise an aryl group. While the aryl group may contain one or more substituents attached thereto, it is particularly preferred that the substituents do not comprise a polar group because it has been found that oxygen, sulfur or nitrogen-containing group decrease the solubility of the additive in fuel oil and, therefore, interferes with the effective use of these additives. On the other hand, the substitution of an alkyl group or groups on the aryl ring is satisfactory and, in some cases, desirable be cause these groups will enhance solubility of the additive in the fuel oil.

Other R groups included within the scope of the present invention comprise an unsaturated heterocyclic ring containing oxygen, sulfur or nitrogen in the ring. Included within this class are groups such as the furan, thiophene, pyrrole, pyridine, quinoline, etc. aswell as compounds containing this configuration such as coumarone, benzothiophene, indole, quinoline, etc.

The preferred compounds are readily prepared by the condensation of benzaldehyde with an alkanol amine. The alkanol amine preferably contains from 2 to about 12 carbon atoms per molecule and thus includes ethanol amine, propanol amine, butanol amine, pentanol amine, hexanol amine, heptanol amine, octanol amine, nonanol amine, decanol amine, undecanol amine and dodecanol amine. It is preferred that the amino group and the hydroxyl group are attached to adjacent carbon atoms. This is readily obtained with ethanol amine, isopropanol amine (2 hydroxy propyl amine), 2 hydroxy butyl amine, 1-amino-2-hydroxy-2-methyl-propane, 1- amino-2-hydroxy-2-methyl-butane, Z-hydroxypentyl amine, 5-amino-4-octanol, etc.

The condensation of benzaldehyde with an al kanol amine is readily effected at room temperature by commingling the two reactants, preferably with stirring. The reaction is exothermic and, when desired, means may be provided to cool the reaction and absorb the heat thereof. The

product then may be treated in any manner to separate the water of reaction from the desired condensation product, and this may be accomplished by distillation under vacuum, azeotropic distillation in the presence of a hydrocarbon solvent, solventextraction with a hydrocarbon such as benzene under liquid phase to form two layers, separating the aqueous layer and subsequently distilling the benzene from the desired condensation product. -It is understood that any. suitable method of preparing these compounds is included within the scope of the present invention. I

. The preferred compounds prepared in the manner hereinbefore set forth include benzalaminoethanol, benzalaminopropanol, benzalaminobutanol, benzalaminopentanol, etc., the preferred additives preferably contain from about 9,to about 20 carbon atoms per molecule. As hereinbefore set forth, when desired the aryl ring may contain hydrocarbon groups attached thereto and particularly alkyl groups.

When the cyclic group comprises an unsaturated heterocyclic ring as hereinbefore set forth, the desired additive may be preparedby the condensation of the corresponding aldehyde with an alkanol amine. Thus, furfural may be condensed with the alkanol amine under substantially the same conditions ashereinbefore setforth. It is understood that other suitable methods ofi riteparing the desired product may be employed in accordance with the present invention. However, it is understood that the additives prepared in this manner are not necessarily equivalent" to those prepared from an aromatic aldehyde.

The additives of the present invention and particularly those prepared from befiz'aildehy'de offer numerous advantages over other additives for this purpose. invention are comparatively low in cost, being prepared from rather cheap starting materials? Further, these additives are readily soluble i zi fuel oils and are not readily extracted by caustic or Water.

The additives of the present invention are added to fuel oils in amounts of lessthah about 1- and preferably in an-amo'unt' of from about G-.0005%. toabout 01% by weight. It is" understood that these additives may be" used in conjunction-with other additives, su'cl'iasmetaldeactivators. antioxidants and" p'r'efe'r'alc'ilyantioiri dants-o'i the phenolic type, syriergi's'ts, ceta'ne irriprovera/ additives which are incbr-porated: for improving: burning. properties of the oil, etc.

Fuel-"oils at thepresent' time are g'enerallyiobtained from two-major sources. one of these sources comprises the non-destructive distilla tion: ofpetroleum oil andthe fuel oil. so obtained is gen'erally' refer-red to ir-r the artas straight or virgins fueloil.- The other majorsource is from catalytic and-noncatalytic cracking rocessesand these fueloilsare generally referred td- 'in the: art as cycle stocks The term cycle stock-- isused because the fuel oil is separated from a fraction which is recycledto the cracking process for further con-version therein. Many commercial-fuel oilscom-prise a-mixture of" virgin oil and cycle stock. the-past fuel oils have come 'mestly from virgindisti'llatesbut, with: the increasing amount of catalytic crackingprocesses being installed; a considerable quantity of catalyticcycle stock-isavail-able and is-beingused for fuel oil-a The properties ot the fuel oils vary considerably depending upon the source ofthe originarlcrude" o-il and this difference inproperti'e's iscarried through: to the cycle stocks. Eurther, blends-of: th'e and cycle stocks-appear towmdergo discoloration to a greater extentthan the'unbl-ended oils; and :the present invention-is, therefore; particularlyadvantageousfor usewith the loleirdedoilsf In View of the difi'e'rence in'properties ot the various oils, their responseto the additives of the: present invention will: accordingly vary. Hovimvea. alt oi the'sa oil's will be improved by treatment with the additive of the: presentin' vention: Further, while"ril rese oils-will vary-conesiderably among themselves, they'vary more so from gasoline: and: other lighter products; i fi'soram as responsew additives is concerned; Thus, certain: inhibitors which are used: in: gasoline and mama: serve to retard deterioration thereof wili be of no value and in: somecases'even'may be harmfiulwhen utilized in fuel: oils: Thus, for example} when 0.02% by Weight a=naphthol or .pyrogallol' wasadded-ta a iuel oil blend of virgin and catalytic cycle stocks,sedimentformation m= over doubleover those obtained im the at'sence: ofiadded material. d-n'ap'hthol and pyrogallol are generally considered as satistae-L The additives of the present" tory gasoline inhibitors but in the case of fuel oils they actually proved harmful. Similarly, a metal deactivator comprising disalicylalpropylene diamine, when added to another sample of the-fuel oil blend mentioned above, ineffect'iv'e' to retard se'd'iment'fo'rmatiori in" the fuel oil. The same general conclusions are applied to the discoloration of fuel oils and it definitely has been established that" there is no correlation between the use of certain compounds in gasoline as compared to their use in fuel oil.

hereinbefore set forth, the properties of fuel oils vary considerably and, when confronted a fuelioilJwhich does not seem to be particularly responsive to the application of additives, itmay be desirable to subject the fuel oil td a p'reliminary treatment such as with caustic acid clay treating, etc. Such treatments have proved beneficial in improving the properties of the fuel oil to respond to the application of addit'ivesj and it' is within the scope of the present invention to employ such treatments in conjunctionwi'th th'eap'plicati'on of the' additives herein set-forth.

Thefollowingexamples are introduced to illustrate" the" novelty and utility of the present invenues butnot the: intention of unduly limitingthe sam'e".

T he fuel oil used-inthis-example was a typical #2 fuel oil comprising catalytic cycle stock-resulting from the cracking. of" Mid continent. oil. Thdfdeloil l-i-ad an- A. I. gravity at 60 E1 of 30.3;an initial boiling point of 422 Harman end: boilingtpoint oi 603 F.-

Discolorationotthe fuel" oil was determined in an accelerated test-in whichsa sample of the fuel oil is placed in a constant temperature" oil bathmai-ntained at 212 F. andthe color determined after 2G h'OHIS: The-color was determined by the A; S: T. Photoelectric Color Method as diescribed'irrthe As T-. M.v Standards oII-Petro leum Products and Lubricants, page 6l 5', October 19 m semen;

additive used in this example was benzal aminopropanol" prepared inthe manner hereinhe'fo're setforth. 0.03% byweightof the additivewa's'added" tdthefuel oil, and the results of these tests-are shown. in the following table. lifefgg'e the test the fuel oil had a color index 0 fuel oil used in thisexample was a typical #2 fuel oil and had aboilingrange of fromabout 460 F. to about'620 F. This fuel oil was subjected to caustic washing. prior to the addition of: benzalaminopropano-l, and the" samples were tested-inthe-manner-hereinbefore set forth. The

results of these tests are shown in the following table:

Here again it will be noted that the benzalaminopropanol served to retard discoloration to a considerable extent, and also that the caustic treatment improved the response of the fuel oil to treatment with the additive.

EXAMPLE III Table 3 A. S. 'l. M. Photoelectric Color Index Additive None 60. 5 About 0.01% by weight of furiuralaminoethanoLn. 88

It will be noted from the data in the above table that the furfuralaminoethanol also served to retard discoloration to a considerable extent.

EXAIVIPLE IV This example shows the superiority of the condensation products of the present invention over aliphatic amin hydroxy compounds as typified by 5-amino-4-octanol. In a series of storage tests of samples of the blend described in Example III, the following results were obtained with various additives.

Table 4 A. S. T. M. Photoelectric Color Index Insoluble Gum Mg./ 100 m1.

Additive None, after 81 days 0.01% by weight of amino octanol,

after 77 days 0.01% by weight of benzalaminoethanol after 77 days 0.01% by weight of furfuralaminoethanol after 77 days It will be noted that all of the above inhibitors retarded gum formation to a considerable extent but that the benzalaminoethanol and furfuralaminoethanol retarded discoloration to a considerable extent, whereas the amino octanol did not serve to retard color formation to the extent obtained with the other additives.

6 EXAMPLE V This example illustrates the effectiveness of benzalaminoethanol, prepared in accordance with the teachings of the present invention, as compared with benzylaminoethanol, prepared by reduction of the benzalaminoethanol. The fuel oil used in this example is a, typical #2 fuel oil comprising a blend of 25% virgin and catalytic cycle stocks from a Mid-Continent crude. Different samples of the crude containing 0.01% by weight of benzalaminoethanol and of benzylaminoethanol were stored at F. for 111 days. The results of these tests are indicated in the following table:

Table 5 A. S. T. M. Insoluble Additive Photoelectric Gum Mg./

Color Index 100 ml.

Benzalaminoethauol 88 0. 4 Denzylaminoethanol 73 l. 1

It will be noted that the benzalaminoethanol is considerably better, both insofar as color and gum formation, than the benzylaminoethanol.

We claim as our invention:

1. A fuel oil heavier than gasoline containing, as a retarder of discoloration, a compound seleqted from the group consisting of a benzalaminoalkanol and a furfuralaminoalkanol, the alkanol group of said compound containing from about 2 to about 12 carbon atoms. I

2. A fuel oil heavier than gasoline containing, as a retarder of discoloration, a benzalaminoalkanol in which the alkanol group contains from about 2 to about 12 carbon atoms.

3. A fuel oil heavier than gasoline containing, as a retarder of discoloration, a furfuralaminoalkanol in which the alkanol group contains from about 2 to about 12 carbon atoms.

4. A fuel oil heavier than gasoline containing, as a retarder of discoloration, benzalaminoethan01.

5. A fuel oil heavier than gasoline containing, as a retarder of discoloration, benzalaminobutanol.

6. A fuel oil heavier than gasoline containing, as a retarder of discoloration, benzalaminopentanol.

7. A fuel oil heavier than gasoline containing, as a retarder of discoloration, benzalaminopropanol.

8. A fuel oil heavier than gasoline containing, as a retarder of discoloration, furfuralaminoethanol.

RALPH B. THOMPSON. JOSEPH A. CHENICEK.

References Cited in the file of this patent UNITED STATES PATENTS Number 

1. A FUEL OIL HEAVIER THAN GASOLINE CONTAINING, AS A RETARDER OF DISCOLORATION, A COMPOUND SELECTED FROM THE GROUP CONSISTING OF A BENZALAMINOALKANOL AND A FURFURALIMINALKANOL, THE ALKANOL GROUP OF SAID COMPOUND CONTAINING FROM ABOUT 2 TO ABOUT 12 CARBON ATOMS. 